A routing protocol is a protocol that specifies how routers communicate with each other for distributing information that enables them to select routes in a data transfer network. Each router has a priori knowledge only of areas of the data transfer network attached to it directly. A routing protocol advertises this information first among immediate neighbor routers, and then throughout the data transfer network. This way, routers gain knowledge of the topology of the data transfer network. For example, in a Border Gateway Protocol (“BGP”), prefixes and their related attributes received at a router from its neighbor routers are first organized to an Adjacency route information-base for Incoming information “Adj_Rib_In”. This information-base is then pruned so that e.g. unnecessary duplicates are removed. The result constitutes a Local information-base “Loc_Rib”. The prefixes and their related attributes contained in the Loc_Rib are advertised, according to appropriate policies, to neighbor routers in order to make the neighbor routers aware of network areas, i.e. sub-networks corresponding to the prefixes, which are accessible via the router under consideration. Traditionally, the advertising to neighbor routers is carried out so that an Adjacency route information-base for outgoing information “Adj_Rib_Out” is created for each neighbor router. Each Adj_Rib_Out is logically a list of prefixes and their related attributes which are to be advertised to the neighbor router related to that particular Adj_Rib_Out. An Adj_Rib_Out can be, for example, a linked list where each prefix is associated with a forward pointer pointing to a next prefix and a backward pointer pointing to a previous prefix on the list constituting the Adj_Rib_Out. The Adj_Rib_Out is constructed for each neighbor router so that policy appropriate for that neighbor router is applied to the prefixes and their related attributes contained in the Loc_Rib. The advertising process for each neighbor router proceeds along the Adj_Rib_Out related to that neighbor router so that those prefixes and their associate attributes that still are to be advertised are sent to the neighbor router under consideration. The problem associated with the advertisement process briefly described above is that the total memory space needed for the Adj_Rib_Out:s grows very strongly when the size of the data transfer network grows. This is due to the fact that both the number of the Adj_Rib_Out:s and the number of entries in each Adj_Rib_Out increase when the size of the data transfer network grows, and thus the memory consumption is proportional to the product of these two numbers. Thus the scalability is limited.